Golf ball with vapor barrier layer and method of making same

ABSTRACT

A golf ball with at least one moisture vapor barrier layer is disclosed. In accordance to one aspect of the invention, the moisture vapor barrier layer may comprise butyl rubber. The butyl rubber may also be a halogenated butyl rubber such as bromobutyl rubber or chlorobutyl rubber. The butyl rubber may also be a sulfonated butyl rubber. The butyl rubber may be blended with other polymers. In accordance to another aspect of the invention, the moisture vapor barrier layer is placed on to a core subassembly and cured by infrared radiation (IR). IR-curable moisture vapor barrier materials include, but not limited to, butyl rubber, polysulfide rubber and single-pack castable polymers, among others. In accordance to another aspect of the invention, an outer layer of the golf ball may comprise a polymer that has a cured temperature greater than the softening temperature or melting temperature of the encased subassembly. Such outer layer may be cured by IR. The outer layer may be a cover, an intermediate layer or a moisture vapor barrier layer.

STATEMENT OF RELATED PATENT APPLICATION

[0001] This non-provisional utility patent application is a continuationof co-pending U.S. patent application Ser. No. 10/103,414, filed on Mar.21, 2002, which is a continuation-in-part of U.S. patent applicationSer. No. 09/973,342, filed on Oct. 9, 2001, now U.S. Pat. No. 6,632,147.The parent application and patent are hereby incorporated by referencein their entirety.

FIELD OF THE INVENTION

[0002] The present invention relates to a novel structure for a golfball, and more particularly to a golf ball with a moisture vapor barrierlayer.

BACKGROUND OF THE INVENTION

[0003] Solid core golf balls are well known in the art. Typically, thecore is made from polybutadiene rubber material, which provides theprimary source of resiliency for the golf ball. U.S. Pat. Nos. 3,241,834and 3,313,545 disclose the early work in polybutadiene chemistry. It isalso known in the art that increasing the cross-link density ofpolybutadiene can increase the resiliency of the core. The core istypically protected by a cover from repeated impacts from golf clubs.The golf ball may comprise additional layers, which can be an outer coreor an inner cover layer. One or more of these additional layers may be awound layer of stretched elastic windings to increase the ball'sresiliency.

[0004] A known drawback of polybutadiene cores cross-linked withperoxide and/or zinc diacrylate is that this material is adverselyaffected by moisture. Water moisture vapor reduces the resiliency of thecores and degrades its properties. A polybutadiene core will absorbwater and loose its resilience. Thus, these cores must be coveredquickly to maintain optimum ball properties. The cover is typically madefrom ionomer resins, balata, and urethane, among other materials. Theionomer covers, particularly the harder ionomers, offer some protectionagainst the penetration of water vapor. However, it is more difficult tocontrol or impart spin to balls with hard covers. Conventional urethanecovers, on the other hand, while providing better ball control, offerless resistance to water vapor than ionomer covers.

[0005] Prolonged exposure to high humidity and elevated temperature maybe sufficient to allow water vapor to invade the cores of somecommercially available golf balls. For example at 110° F. and 90%humidity for a sixty day period, significant amounts of moisture enterthe cores and reduce the initial velocity of the balls by 1.8 ft/s to4.0 ft/s or greater. The change in compression may vary from 5 PGA toabout 10 PGA or greater. The absorbed water vapor also reduces thecoefficient of restitution (CoR) of the ball.

[0006] Several prior patents have addressed the water vapor absorptionproblem. U.S. Pat. No. 5,820,488 discloses a golf ball with a solidinner core, an outer core and a water vapor barrier layer disposedtherebetween. The water vapor barrier layer preferably has a water vaportransmission rate lower than that of the cover layer. The water vaporbarrier layer can be a polyvinylidene chloride (PVDC) layer. It can alsobe formed by an in situ reaction between a barrier-forming material andthe outer surface of the core. Alternatively, the water vapor barrierlayer can be a vermiculite layer. U.S. Pat. Nos. 5,885,172 and 6,132,324disclose, among other things, a golf ball with a polybutadiene or woundcore with an ionomer resin inner cover and a relatively soft outercover. The hard ionomer inner cover offers some resistance to watervapor penetration and the soft outer cover provides the desirable ballcontrol. Additionally, U.S. Pat. No. 5,875,891 discloses an impermeablepackaging for golf balls. The impermeable packaging acts as a moisturebarrier to limit moisture absorption by golf balls during storage, butnot during use.

[0007] The moisture vapor barrier layer disclosed in the prior patentscan be rigid and makes the ball stiffer. Furthermore, producing a rigidlayer may cause significant production obstacles. On the other hand,less rigid polymers, such as butyl rubber and other rubbers, are knownto have low permeability to air, gases and moisture. Butyl rubber iswidely used as sealant for rooftops, as inner liner in tubeless tires,and as lining for chemical tanks, among other uses. In the golf ballart, butyl rubber's usage has been limited to practice balls or drivingrange balls due to its slow initial velocity and low CoR, as discussedin U.S. Pat. Nos. 5,209,485 and 4,995,613. Butyl rubber is also used asthe outermost cover layer or a part of the cover due to its durability,as disclosed in U.S. Pat. Nos. 5,873,796 and 5,882,567, among others.However, the moisture vapor barrier advantage of butyl rubber has notheretofore been utilized in the golf ball art to make a betterperforming golf ball.

[0008] Also, high-temperature curing of certain polymeric materials toform the water vapor barrier layer or other outer layers on the golfball is difficult to accomplish, since such curing or crosslinking heatsthe entire golf ball subassembly. This heating method may degrade theuntargeted components or layers within the subassembly. Additionally,this curing method limits suitable outer layer materials to materialshaving a cured temperature that is lower than the softening temperatureor lower melting temperature of the inner layers or core.

[0009] Hence, there remains a need for a golf ball with an improvedwater vapor barrier layer and improved methods for applying a watervapor barrier layer on to the core of the golf ball.

SUMMARY OF THE INVENTION

[0010] The present invention is directed to a golf ball comprising alayer of moisture vapor barrier with a moisture vapor transmission ratepreferably lower than that of the cover. Preferably, the moisture vaporbarrier layer comprises butyl rubber. The butyl rubber may also be ahalogenated butyl rubber such as bromobutyl rubber or chlorobutylrubber. The butyl rubber may also be a sulfonated butyl rubber. Thebutyl rubber may be blended with other polymers, such as doublebond-vulcanizable rubber, ethylene propylene diene monomer rubber andvinylidene chloride.

[0011] The present invention is also directed to a golf ball comprisinga moisture vapor barrier layer, which comprises copolymer of isobutyleneand p-methylstyrene or polyisobutylene.

[0012] In accordance to another aspect of the invention, the moisturevapor barrier layer is placed on to a core subassembly and cured byinfrared radiation (IR). IR-curable moisture vapor barrier materialsinclude, but not limited to, butyl rubber, polysulfide rubber andsingle-pack castable polymers, among others.

[0013] In accordance to another aspect of the invention, an outer layerof the golf ball may comprise a polymer that has a cured temperaturegreater than the softening temperature or melting temperature of theencased subassembly. Such outer layer may be cured by IR. The outerlayer may be a cover, an intermediate layer or a moisture vapor barrierlayer.

[0014] The present invention is also directed to a golf ball comprisinga butyl rubber moisture vapor barrier and a relatively soft cover.Preferably, the soft cover has a Shore D of less than 65 or betweenabout 30 and about 60, and more preferably between about 35 and about50, and most preferably about 40 and about 45. The cover preferably hasa thickness of between about 0.010 inch to about 0.050 inch, and morepreferably about 0.030 inch. The cover preferably comprises a thermosetpolymer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In the accompanying drawings which form a part of thespecification and are to be read in conjunction therewith and in whichlike reference numerals are used to indicate like parts in the variousviews:

[0016]FIG. 1 is a front view of a dimpled golf ball in accordance to thepresent invention;

[0017]FIG. 2 is a cross-sectional view of the golf ball in FIG. 1showing a solid core surrounded by a thin moisture vapor barrier layerand a cover; and

[0018]FIG. 3 is a cross-sectional view of another golf ball inaccordance to the present invention showing a solid core with multiplewound layers surrounded by a thin moisture vapor barrier layer.

DETAILED DESCRIPTION OF THE INVENTION

[0019] As shown generally in FIGS. 1 and 2, where like numbers designatelike parts, reference number 10 broadly designates a golf ball inaccordance to the present invention. Golf ball 10 preferably has a solidcore 12, an intermediate layer 14 and a cover 16. Solid core 12 maycomprise a single spherical element, or it may comprise a sphericalelement with one or more intermediate layers surrounding the sphericalelement. Solid core 12 can be made from any suitable core materialsincluding thermoset plastics, such as natural rubber, polybutadiene(PBD), polyisoprene, styrene-butadiene or styrene-propylene-dienerubber, and thermoplastics such as ionomer resins, polyamides,polyesters, or a thermoplastic elastomer. Suitable thermoplasticelastomers include Pebax®, which is believed to comprise polyether amidecopolymers, Hytrel®, which is believed to comprise polyether estercopolymers, thermoplastic urethane, and Kraton®, which is believed tocomprise styrenic block copolymers elastomers. These products arecommercially available from Elf-Atochem, E.I. Du Pont de Nemours andCompany, various manufacturers, and Shell Chemical Company,respectively. The core materials can also be formed from a castablematerial. Suitable castable materials include those comprising aurethane, polyurea, epoxy, silicone, IPN's, etc.

[0020] Additionally, suitable core materials may also include a reactioninjection molded polyurethane or polyurea, including those versionsreferred to as nucleated, where a gas, typically nitrogen, isincorporated via intensive agitation or mixing into at least onecomponent of the polyurethane, typically, the pre-polymer, prior tocomponent injection into a closed mold where essentially full reactiontakes place resulting in a cured polymer having reduced specificgravity. These materials are referred to as reaction injection molded(RIM) materials. Alternatively, the core may have a liquid center.

[0021] Cover 16 is preferably tough, cut-resistant, and selected fromconventional materials used as golf ball covers based on the desiredperformance characteristics. The cover may comprise one or more layers.Suitable cover materials include ionomer resins, such as Surlyn®available from DuPont, blends of ionomer resins, thermoplastic orthermoset urethane, acrylic acid, methacrylic acid, thermoplastic rubberpolymers consisting of block copolymers in which the elastomericmidblock of the molecule is an unsaturated rubber or a saturated olefinrubber, e.g., Kraton® rubbers available from Shell Chemical Co.,polyethylene, and synthetic or natural vulcanized rubber such as balata.

[0022] Additionally, other suitable core and cover materials aredisclosed in U.S. Pat. No. 5,919,100 and international publications WO00/23519 and WO 01/29129. These disclosures are incorporated byreference in their entirety. Preferably, core 12 is made from apolybutadiene rubber material and cover 16 is made from a compositioncomprising a thermoset or thermoplastic urethane or a compositioncomprising an ionomer resin.

[0023] To prevent or minimize the penetration of moisture, typicallywater vapor, into core 12 of golf ball 10, intermediate layer 14comprises a moisture vapor barrier layer preferably disposed around core12. Preferably, moisture vapor barrier layer 14 has a moisture vaportransmission rate that is lower than that of the cover, and morepreferably less than the moisture vapor transmission rate of an ionomerresin such as Surlyn® which is in the range of about 0.45 to about 0.95grams·mm/m²·day. Typically, the moisture vapor transmission rate ofionomer resin is less than 0.6 grams·mm/m²·day as reported in“Permeability and other Film Properties of Plastics and Elastomer”published by the Plastic Design Library (1995). The moisture vaportransmission rate is defined as the mass of moisture vapor that diffusesinto a material of a given thickness per unit area per unit time. Thepreferred standards of measuring the moisture vapor transmission rateinclude ASTM F1249-90 entitled “Standard Test Method for Water VaporTransmission Rate Through Plastic Film and Sheeting Using a ModulatedInfrared Sensor,” and ASTM F372-94 entitled “Standard Test Method forWater Vapor Transmission Rate of Flexible Barrier Materials Using anInfrared Detection Technique,” among others.

[0024] A preferred polymer for the moisture vapor barrier layer is butylrubber. Butyl rubber (IIR) is an elastomeric copolymer of isobutyleneand isoprene. Detailed discussions of butyl rubber are provided in U.S.Pat. Nos. 3,642,728, 2,356,128 and 3,099,644. The disclosures of thesereferences are incorporated herein by reference in their entireties.Butyl rubber is an amorphous, non-polar polymer with good oxidative andthermal stability, good permanent flexibility and high moisture and gasresistance. Generally, butyl rubber includes copolymers of about 70% to99.5% by weight of an isoolefin, which has about 4 to 7 carbon atoms,e.g., isobutylene, and about 0.5% to 30% by weight of a conjugatedmultiolefin, which has about 4 to 14 carbon atoms, e.g., isoprene. Theresulting copolymer contains about 85% to about 99.8% by weight ofcombined isoolefin and 0.2% to 15% of combined multiolefin. Commerciallyavailable butyl rubbers, such as those manufactured by ExxonMobilChemical Company, typically have about 1 to 2.5 mole percent ofisoprene. Butyl rubbers generally have molecular weight of about 20,000to about 500,000. Suitable butyl rubber is also available from UnitedCoatings under the tradename Elastron™ 858. Elastrom 858 is a butylrubber coating applied as a solution in a volatile hydrocarbon solvent,which is typically sprayed or dipped on to an object or a surface, andcontains lead peroxide as a crosslinking agent.

[0025] Butyl rubbers are also available in halogenated form. Halogenatedbutyl rubbers may be prepared by halogenating butyl rubber in a solutioncontaining inert C3-C5 hydrocarbon solvent, such as pentane, hexane orheptane, and contacting this solution with a halogen gas for apredetermined amount of time, whereby halogenated butyl rubber and ahydrogen halide are formed. The halogenated butyl rubber copolymer maycontain up to one halogen atom per double bond. Halogenated butylrubbers or halobutyl rubbers include bromobutyl rubber, which maycontain up to 3% reactive bromine, and chlorobutyl rubber, which maycontain up to 3% reactive chlorine. Halogenated butyl rubbers are alsoavailable from ExxonMobil Chemical. Butyl rubbers and halogenatedrubbers advantageously have low permeability to air, gases and moisture.For example, as reported by the manufacturer the permeability ofnitrogen in butyl rubber is more than one order of magnitude less thanthat in neoprene, styrene butadiene rubber, natural rubber and nitrilebutadiene rubber.

[0026] Butyl rubber is also available in sulfonated form, such as thosedisclosed in the '728 patent and in U.S. Pat. No. 4,229,337. Generally,butyl rubber having a viscosity average molecular weight in the range ofabout 5,000 to 85,000 and a mole percent unsaturation of about 3% toabout 4% may be sulfonated with a sulfonating agent comprising a sulfurtrioxide (SO₃) donor in combination with a Lewis base containing oxygen,nitrogen or phosphorus. The Lewis base serves as a complexing agent forthe SO₃ donor. SO₃ donor includes compound containing available SO₃,such as chlorosulfonic acid, fluorosulfonic acid, sulfuric acid andoleum.

[0027] Typically, the moisture vapor transmission rate of butyl rubberis in the range of about 0.001 to about 0.100 grams·mm/m²·day.

[0028] Other suitable moisture vapor barrier polymers include theelastomers that combine the low permeability of butyl rubbers with theenvironmental and aging resistance of ethylene propylene diene monomerrubbers (EPDM), commercially available as Exxpro™ from ExxonMobilChemical. More specifically, these elastomers are brominated polymersderived from a copolymer of isobutylene (IB) and p-methylstyrene (PMS).Bromination selectively occurs on the PMS methyl group to providereactive benzylic bromine functionality. Another suitable moisture vaporbarrier polymer is copolymer of isobulyline and isoprene with a styreneblock copolymer branching agent to improve manufacturing processability.

[0029] Another suitable moisture vapor barrier polymer ispolyisobutylene. Polyisobutylne is a homopolymer, which is produced bycationic polymerization methods. Commercially available grades ofpolyisobutylene, under the tradename Vistanex™ also from ExxonMobilChemical, are highly paraffinic hydrocarbon polymers composed on longstraight chain molecules containing only chain-end olefinic bonds. Anadvantage of such elastomer is the combination of low permeability andchemical inertness to resist moisture vapor encroachment, and chemicalor oxidative attacks. Polyisobutylene is available as a viscous liquidor semi-solids, and can be dissolved in certain hydrocarbon solvents.

[0030] In accordance to another aspect of the invention, halogenatedbutyl rubber can be blended with a second rubber, preferably a doublebond-vulcanizable rubber, in a specific mixing ratio in a two-stepkneading process and then cured to form a rubber blend that has lowair/vapor permeability and high adhesion to diene rubbers. A clearadvantage of this rubber blend is that it provides enhanced adherence toa polybutadiene core or subassembly to provide an enhancedmoisture/water vapor barrier layer. This rubber blend is discussed inU.S. Pat. No. 6,342,567 B2. The '567 patent is hereby incorporatedherein by reference. Alternatively, a brominatedisobutylene/p-methylstyrene, discussed above, can be used in place ofthe halogenated rubber. Other moisture vapor barrier polymers includethermoplastic elastomer blends that may be dynamically vulcanized andcomprise a butyl rubber or a halogenated butyl rubber, such as thosediscussed in U.S. Pat. Nos. 6,062,283, 6,334,919 B1 and 6,346,571 B1.These references are incorporated herein by reference. Alternatively,butyl rubber may be blended with a vinylidene chloride polymer, i.e.,saran, as disclosed in U.S. Pat. No. 4,239,799. The '799 patent is alsoincorporated herein by reference.

[0031] Butyl rubbers can be cured by a number of curing agents.Preferred curing agents for golf ball usage include sulphur for butylrubber, and a peroxide curing agent, preferably zinc oxide, forhalogenated butyl rubbers. Other suitable curing agents may includeantimony oxide, lead oxide or lead peroxide. Lead based curing agentsmay be used when appropriate safety precautions are implemented. Butylrubbers are commercially available in various grades from viscous liquidto solids with varying the degree of unsaturation and molecular weights.Latex grades are also available.

[0032] Butyl rubber and halogenated rubber can be processed by milling,calendering, extruding, injection molding and compression molding, amongother techniques. These processing techniques can produce a semi-curedsheets or half-shelves of the moisture vapor barrier material, which canbe wrapped around a core or a core subassembly. The moisture vaporbarrier can be fully cured by exposure to heat at elevated temperaturestypically in the range of about 250° F. to 2000° F.

[0033] Additionally, any number of fillers, additives, fibers andflakes, such as mica, micaceous iron oxide, metal, ceramic, graphite,aluminum or more preferably leafing aluminum, can be incorporated intothe moisture vapor barrier layer to create a physical barrier, i.e., amore tortuous path, against moisture vapor encroachment.

[0034] In accordance to another aspect of the invention, the curing ofthe moisture vapor barrier material on to the core or the coresubassembly is preferably accomplished by infrared radiation (IR). IRadvantageously heats the moisture vapor material, e.g., butyl rubber,locally without penetrating the underlying golf ball core and/or otherencased layers. Hence, the predetermined properties of the core and/orof the encased layers would not be affected by the heating/curing of themoisture vapor barrier layer. U.S. Pat. No. 6,174,388 B1 discloses thatIR can be used effectively to heat and cure the surface of a polymericobject while leaving the other portions of the object unchanged. U.S.Pat. Nos. 5,677,362 and 5,672,393 disclose that IR heating can be usedin conjunction with ultraviolet heating to cure polymers effectively.The disclosures of the patents are incorporated by reference in theirentirety.

[0035] Another advantage of using IR as the curing technique is thatsuitable moisture vapor barrier polymers, which have cured orcross-linking temperatures that are higher than the softeningtemperature or the melting temperature of the materials encased therein,can be now employed as the moisture vapor barrier layer and/or otherouter layers.

[0036] In accordance to another aspect of the present invention, anothersuitable IR-cured water vapor barrier material is polysulfide rubberincluding those disclosed in U.S. Pat. Nos. 4,263,078 and 4,165,425,among others. These references are incorporated herein by reference. Inone example, the polysulfide rubber is cured with lower alkyl tin oxide,such as di-n-butyl tin oxide, and used in hot applied processes asdisclosed in the '425 patent. This particular polysulfide rubber isthiol terminated and cured with the lower alkyl tin oxide attemperatures between 100° C. and 300° C. to become a solid thermoplasticelastomer that can be softened by heating and then cast or injectionmolded into a water vapor barrier layer. This polysulfide compound ispreferably cured by IR.

[0037] Another suitable IR-curable polysulfide rubber is based on thiolterminated liquid polysulfide polymer cured with zinc oxide and a sulfurcontaining compound selected from 2-mercaptobenzothiazol, zinc loweralkyl dithiocarbamate and alkyl thiuram polysulfides at temperaturesfrom about 200° F. to about 390° F. Agents, which improve the flowingproperties of the composition, such as copolymers of styrene andalkylenes, organic or inorganic reinforcing fibrous materials, phenolicresins, coumarone-indene resins, antioxidants, heat stabilizers,polyalkylene polymers, factice, terpene resins, terpene resins esters,benzothiazyl disulfide or diphenyl guanidine, can also be added to thecomposition. Advantageously, this polysulfide rubber possesses a goodability to wet the substrate and forms good bonds with such substratewhen cooled and, therefore, is a preferred sealant for the golf ballcore. This polysulfide compound is also preferably cured by IR.

[0038] Moisture vapor barrier layer comprising polysulfide rubber isfully disclosed in co-pending patent application entitled “Golf BallWith Vapor Barrier Layer and Method for Making Same” filed on the sameday as the present application and assigned to the same assignee. Thedisclosure of this co-pending patent application is incorporated hereinby reference.

[0039] In accordance to another aspect of the present invention,suitable IR-cured water vapor barrier polymers include single-packcastable polymers. A preferred single-pack polymer uses uretdiones orblocked isocyanates to form a single-pack urethane component. Thesingle-pack blocked isocyanate system, which preferably comprisesisocyanate combined with an amine or poloyl, is advantageously stable atroom temperature. The application of heat, such as infrared radiation,causes the isocyanate to become unblocked or to react to form aurethane. No mixing or dynamically controlling the ratios of thecomponents is required.

[0040] Uretdione castable materials can be pre-formulated as asingle-pack system without premature reaction. The mixed single-packmaterial can be directly injected or poured into a mold, avoidingmetering and mixing of multiple components. Parts can be made utilizingviscous or solid materials that previously could not be used withtraditional two-pack systems. Advantageously, uretdiones and blockedisocyanates when combined with suitable reactive components can bemilled into rubber stock for use with other manufacturing techniques,discussed above.

[0041] A non-limiting example of a single-pack system in accordance tothe present invention is as follows. Finely ground uretdione isdispersed in a liquid polyol or polyamine in combination with a tincatalyst and cyclic amidine catalyst to form a slurry mixture. Theslurry mixture is poured into a suitable golf ball mold to make therequired part, e.g., core, intermediate layer or cover. The mold is thenheated to reach the predetermined deblocking temperature of about150-180° C., and the reaction is allowed sufficient time to complete.The cured component then can be removed from the mold for furtherprocessing, if necessary.

[0042] In another example, 3,5-dimethylpyrazole (DMP) blocked IPDI isused in place of the uretdione in the above example. The mold is thenheated to the deblocking temperature of about 140-160° C., and thereaction is allowed sufficient time to complete. In another non-limitingexample, the single-pack moisture vapor barrier layer utilizes blockedisocyanates that volatilize when de-blocking occurs, such asdiethylmaleonate (DEM) or methyl ethyl ketoxime (MEKO) blockedhexamethylene diisocyanate cyclic trimer. Such an example could besprayed or dipped onto the golf ball core, subassembly or the like andthen followed with an IR cure.

[0043] Non-limiting chemical structures of the single-pack system areshown below:

[0044] Formation of uretdiones:

[0045] Preferred chemical structure of polyuretdione cross-linker:

[0046] The preferred hardeners are uretdiones or blocked isocyanates,where the blocking agent remains in the component as a solid once cast,such as DMP or triazole blocked isocyanates.

[0047] The structures of the preferred blocking agents are:

[0048] Single-pack castable water vapor barrier material is fullydisclosed in parent application Ser. No. 09/973,342, which has beenincorporated by referenced.

[0049] In accordance to one aspect of the invention, the Shore Dhardness values for the core and moisture vapor barrier sub-assemblieshave been measured less than about 60 and more specifically in the rangeof about 5-50. Alternatively, according to other aspects of theinvention, the moisture barrier sub-assemblies may have Shore D hardnessvalue of greater than 50, when more rigid materials, such as stiffionomer with a Shore D hardness of greater than 55 are used inconjunction with the moisture vapor barrier layer 14.

[0050] Preferably, a golf ball in accordance to the present inventioncomprises a solid or multiple-layer solid polybutadiene core 12 havingan outer diameter of greater than about 1.50 inches, more preferably1.550 inches and most preferably about 1.580 inches. Moisture vaporbarrier layer 14 has a thickness preferably in the range of about 0.001inch to about 0.100 inch, more preferably in range of about 0.010 inchto about 0.050 inch and cover 16 is a urethane cover with sufficientthickness to produce a 1.680 inch diameter golf ball.

[0051] More preferably, the moisture vapor barrier layer is a thin layerof suitable butyl rubber polymers discussed above, preferably less than0.050 inch, more preferable less than 0.030 inch and most preferablyless than 0.010 inch. It is also preferable that the butyl rubbermoisture vapor barrier layer would not significantly and negativelyaffect the coefficient of restitution of the golf ball. Preferably, thepolybutadiene core 12 and the thin butyl rubber moisture vapor barrierlayer 14 are covered by a relatively soft polymer cover having athickness from about 0.010 to about 0.050 inch, more preferably about0.030 inch and has a Shore D of less than 65 or from about 30 to about60, more preferably from about 35 to about 50 and even more preferablyabout 40 to about 45. Such a cover is fully disclosed in U.S. Pat. Nos.5,885,172 and 6,132,324. The disclosures of these two patents areincorporated herein by reference in their entireties. Preferred coverpolymers include thermoset urethanes and polyurethanes, thermoseturethane ionomers and thermoset urethane epoxies.

[0052] In accordance to yet another aspect of the invention, as shown inFIG. 3 golf ball 20 may have multiple layer core 12 a, 12 b and 12 c,surrounded by intermediate layer 14 and dimpled cover 16. Core layers 12b and 12 c may be an integral solid layer or discrete layers molded oneach other. Alternatively, both outer core layers 12 b and 12 c could bewound layers, or one of these two layers may be a wound layer, and theinnermost core 12 a may be liquid-filled.

[0053] While various descriptions of the present invention are describedabove, it is understood that the various features of the presentinvention can be used singly or in combination thereof. Therefore, thisinvention is not to be limited to the specifically preferred embodimentsdepicted therein.

What is claimed is:
 1. A golf ball comprising a cover layer encasing asubassembly, the subassembly comprising a moisture vapor barrier layerencasing a core, wherein the moisture vapor barrier layer has a moisturevapor transmission rate of less than about 0.6 grams·mm/m²·day, and isformed from a composition comprising an elastomer and a double-bondvulcanizable rubber.
 2. The golf ball of claim 1, wherein the elastomeris halogenated, sulfonated, or both.
 3. The golf ball of claim 2,wherein the elastomer is halogenated, and comprises at least one of thefollowing: less than about 3% reactive halogen; less than about 1halogen atom per double bond; a benzylic bromine functionality; or abranched styrenic block.
 4. The golf ball of claim 1, wherein theelastomer comprises branched styrenic blocks.
 5. The golf ball of claim1, wherein the elastomer comprises a conjugated multi-olefin or aniso-olefin.
 6. The golf ball of claim 1, wherein the elastomer is acopolymer of p-methylstyrene and isobutylene or a brominated copolymerof p-methylstyrene and isobutylene.
 7. The golf ball of claim 1, whereinthe composition further comprises a filler.
 8. The golf ball of claim 8,wherein the filler is selected from a group consisting of leafingaluminum, mica flakes, micaceous iron oxide flakes, aluminum flakes,ceramic flakes, graphite flakes, and mixtures thereof.
 9. The golf ballof claim 1, wherein the composition further comprises at least onepolymer selected from a group consisting of vinylidene chloride polymersand ionomers.
 10. The golf ball of claim 1, wherein the composition hasa moisture vapor transmission rate of about 0.001 grams·mm/m²·day toabout 0.1 grams·mm/m²·day.
 11. The golf ball of claim 1, wherein thecomposition is a dynamically vulcanizable thermoplastic elastomer blendadhesive to diene rubbers.
 12. The golf ball of claim 1, wherein theelastomer has a molecular weight of about 20,000 to about 500,000. 13.The golf ball of claim 1, wherein the composition forms a tortuous pathagainst moisture vapor encroachment.
 14. The golf ball of claim 1,wherein the composition is applied in a form selected from a groupconsisting of liquid, latex, viscous liquid, semi-solid, solid, and insolvents.
 15. The golf ball of claim 1, wherein the composition is curedby infra red radiation or a combination of infra red and ultra violetradiations.
 16. A golf ball comprising a cover layer encasing asubassembly, the subassembly comprising a moisture vapor barrier layerencasing a core, wherein the moisture vapor barrier layer has a moisturevapor transmission rate of less than about 0.6 grams·mm/m²·day, and isformed from a composition comprising an elastomeric homopolymer orcopolymer that comprises about 0.2% to about 30% by weight of aconjugated multi-olefin having about 4 to about 14 carbon atoms, aniso-olefin having greater than 4 to about 7 carbon atoms, or acombination of the conjugated multi-olefin and the iso-olefin.
 17. Thegolf ball of claim 16, wherein the elastomeric copolymer comprises theconjugated multi-olefin and about 70% to about 99.8% by weight of theiso-olefin.
 18. The golf ball of claim 16, wherein the elastomerichomopolymer or copolymer is amorphous and non-polar.
 19. The golf ballof claim 16, wherein the elastomeric homopolymer or copolymer issulfonated, halogenated, or both; and wherein when halogenated, theelastomeric homopolymer or copolymer comprises at least one of thefollowing: less than about 3% reactive halogen, less than about 1halogen atom per double bond, a benzylic bromine functionality, or abranched styrenic block.
 20. The golf ball of claim 16, wherein theelastomeric homopolymer or copolymer is a highly paraffinic hydrocarbonpolymer composed on long straight chain molecules containing onlychain-end olefinic bonds.
 21. The golf ball of claim 16, wherein theelastomeric copolymer is a copolymer of p-methylstyrene and isobutyleneor a brominated copolymer of p-methylstyrene and isobutylene.
 22. Thegolf ball of claim 16, wherein the composition forms a tortuous pathagainst moisture vapor encroachment.
 23. The golf ball of claim 16,wherein the composition is applied in a form selected from a groupconsisting of liquid, latex, viscous liquid, semi-solid, solid, and insolvents.
 24. The golf ball of claim 16, wherein the composition iscured by infra red radiation or a combination of infra red and ultraviolet radiations.
 25. The golf ball of claim 16, wherein thecomposition further comprises a filler selected from a group consistingof leafing aluminum, mica flakes, micaceous iron oxide flakes, aluminumflakes, ceramic flakes, graphite flakes, and mixtures thereof.